The present invention relates to a cleaning device for use in image forming equipment for removing a toner remaining on an image carrier in the form of a photoconductive element after image transfer by an elastic cleaning blade and discharging the removed toner by a toner discharge coil.
Generally, an electrophotographic copier or similar image forming equipment using an electrophotographic procedure has an image carrier which is implemented as a photoconductive drum. A toner remaining on the drum after the transfer of a toner image from the drum to a paper sheet is removed by a cleaning device. The cleaning device is often implemented by an elastic cleaning blade for scraping off the remaining toner from the drum in contact with the drum, a toner discharge coil for driving the removed toner out of the cleaning device, and a casing accommodating the blade and coil. While this type of cleaning device is in operation, the toner restricted by the cleaning blade sequentially accumulates on the underside of the blade. As soon as the mass of the toner accumulating on the underside of the blade exceeds a certain amount, it sequentially moves downward against the rotation of the drum and falls. The toner fallen from the blade accumulates between the toner coil and the drum and hardens there, resulting in so-called toner blocking. The toner block sequentially grows until it reaches the blade. Such a phenomenon is apt to occur when the fluidity of toner is low, especially when the ambient temperature of the cleaning device is high. The toner block reached the blade urges it upward to produce a substantial gap between the drum and the blade, preventing the cleaning device from cleaning the drum to an expected degree. To eliminate toner blocking, a brush may be held in contact with the drum between the blade and the coil, as already proposed in the art. The brush serves to reduce the amount of toner reaching the blade by bushing off the toner from the drum.
However, although the brush mentioned above may enhance efficient cleaning, it is too expensive to be installed in an inexpensive popular type of copier. Further, the pressure ascribable to the rotation of the brush causes the toner in the cleaning casing to scatter around even to the outside of the casing, resulting in the need for a casing having greater sealability and, therefore, in the increase in cost. For this reason, many of inexpensive copiers do not use such a brush and, therefore, suffer from the previously stated toner blocking.